Greetings:
This is a grossly simplified form of a 3D model I'm doing of an electromechanical switch using the MEMS module.
There's a cantilever which is at zero bias, a "gate" electrode which is biased to a non-zero voltage, and a contact (which for purposed here is at a zero charge state). With a nonzero bias the cantilever is attracted to the gate electrode, bending, but then it makes physical contact with the contact electrode and the gap remains finite, preventing full collapse. If the bias were ramped further, eventually the gap at the gate electrode would also collapse, but this would take very high force.
In any case, I don't get anywhere close to this. I can ramp the bias up to on order 0.1 volts, and then it fails to converge.
I have two approaches. One is a standard "stationary" study in which the gate voltage is specified directly. The other is where the voltage is ramped up proportional to the square of the ramping parameter.
There is a 20 nm gap between the cantilever and the contact electrode but the total deflection at the tip maxes out at 3.6 pm (or milli-nm, if you prefer). So any geometric complexities are still minimal at this point.
I've tried to get this working for days and I'm afraid I'm missing something silly.
Anyone else have experience with these structures?
Link:
www.dropbox.com/s/uvkue4m2xqv5...msolGeometry_2d_clean.mph?dl=0
The electrostatics, which converge only at low bias, are shown here:
i.imgur.com/IKKxXG6.png